Yellow FeverTiffany S. & Tonya C.

Multiple Yellow Fever Viruses at 234,000x mag.

Description of virus that causes the disease.

• Caused by a "flavivirus" called Yellow Fever
• (flavus meaning yellow in Latin)
• Group called Flaviviridae, carried by antropods (mosquitoes, ticks etc.)
• 40-60 nanometers wide
• enveloped RNA virus
• consists of a single strand of RNA

Viral Specificity:

• Main target is the liver
• Also affects the heart, kidneys, glands, adrenal glands
• Skeletal muscle tissue affected
• Hosts are humans (Urban yellow fever) or monkeys (Jungle yellow fever)
• After bitten by infected anthropod the virus enters through the skin
• Travels through the blood stream spreading to the organs
• Liver failure occurs, heart beat slows and adrenal glands stop functioning

Symptoms and progression of the disease:

• Incubation period of 3-6 days
• Symptoms start abruptly (5-6 days) including fever, headache, back pain, extreme exhaustion, nausea, and vomiting.
• Second phase symptoms such as extreme fever, jaundice (due to liver damage), liver & kidney failure, and bleeding in the mouth, skin, and gastrointestinal tract
• After 3-4 days of symptoms the host usually begins healing lasting hours to days
• Then the "Yellow Phase" including severe symptoms such as liver inflammation, jaundice, black vommit, high fever, hemorrhaging, confusion, bleeding into the skin, coma & death
• If the host recovers from the "Yellow Phase" they go into remission
• Undergoes a lytic cycle in both the mosquito and human body (liver cells)

Symptoms of Yellow Fever

Common Methods of Transmission:

• Transmitted through infected mosquitoes

• Not passed from human to human
• Three different infectious cycles
• Urban cycle:
• Human infected in densely populated areas
• one or many infected mosquitoes pass it to large numbers of humans
• common cause of yellow fever outbreaks
• Sylvatic cycle:
• in the jungle, monkeys
• infected monkeys pass the virus to other mosquitoes
• can rarely occur to humans working in rainforest
• Savannah cycle:
• can infect humans or monkeys
• in humid areas, most common in Africa

Treatment and Prevention:

• Yellow fever vaccine exists
• Avoidance of mosquito bites (covering of exposed skin/repellent)
• Rest & fluids is crucial to reduce symptoms
• Hospitalization
• No cure exsists once acquired

Vaccine being given

Miscellaneous:

• 90% of cases occur in Africa, 10% in South America
• Originated in Africa, spread to West Africa
• Carried to Yucatan by ship in 1648
• For hundreds of years people had no idea what caused Yellow Fever
• Major outbreaks in South America
• Carried to United States (mainly Philadelphia)
• Caused George Washington to flee

Resources accessed:

Author: Mary T. Busowski

Title of article: Yellow Fever

Url: http://emedicine.medscape.com/article/232244-overview

Date: April 17, 2009

Author: Judy Arbigue
Title of article: Yellow Fever - The Disease & Symptoms
Url: http://www.suite101.com/content/yellow-fever-a12900
Date: February 7, 2007

Author: Mama's Health copyright
Title: Yellow Fever
Url: http://www.mamashealth.com/yellow.asp
Date: Oct. 23, 2010